This invention relates to optical communications technology, and particularly to a system and method for providing a slab optical multiplexer.
Multiplexers are a common optical component of telecommunications technology. These devices receive a multiplicity of input optical beams having different wavelengths and superimpose them into a common optical output beam. Traditional multiplexing devices are typically based on prism/grating and refractive lens combinations, optical band-pass filters, or waveguide coupling. For free-space light propagation, prism/grating and refractive lens combination multiplexers are used. In such devices, the lens focuses multiple beams into a single output fiber. But a single collecting lens must be relatively large to intercept all beams of interest. Hence this scheme is difficult to miniaturize. Moreover, devices comprising multiple separate optical components require difficult and time-consuming optical alignment.
In a first embodiment disclosed herein, a slab optical multiplexer is provided. The multiplexer comprises a slab substrate having two substantially flat and parallel surfaces, and internally propagating light beams. The multiplexer further comprises collimating/focusing optical elements and micro-diffractive optical elements each positioned in the light beams on the surfaces. At least one micro-diffractive optical element is positioned simultaneously in two separately incident and intersecting light beams, such that the two separately incident light beams are diffracted into a pair of co-propagating diffracted light beams.
In another embodiment disclosed herein, a method of multiplexing input light beams of differing wavelengths is provided. The method comprises providing a slab of material comprising opposed major surfaces, and receiving externally incident input light beams of differing wavelengths. The method further comprises diffracting two externally incident light beams at major surfaces of the slab into a superimposed pair of co-propagating diffracted light beams containing superimposed wavelength components of the two externally incident input light beams.
In yet another embodiment disclosed herein, a method of fabricating a slab optical multiplexer is provided. The method comprises providing a slab substrate of optically transmissive material, having flat and parallel opposing surfaces. The method further comprises forming micro-optical elements at the parallel surfaces, in which the micro-optical elements are selected from collimating/focusing elements and micro-diffractive optical elements.